Neatly packaged, multi-piece manipulable puzzles are popular for recreation and amusement. The interest for new and mentally challenging manipulable ("brainteaser") puzzles continues to grow, even in the face of the ubiquitous and increasingly sophisticated electronic amusement devices. "Brainteaser" inventions naturally augment recreation yet allow relaxed thoughtful self-improvement. A very popular form of manipulable puzzles is the portable and self-contained type, which allows the user to define the desired level of activity and interruption without necessarily disrupting the user's progress. Also such puzzles foster collateral benefits such as promoting analytical thinking by requiring the user to predict the result of each particular manipulation as well as some enhancement of hand-eye coordination.
Restricted movement sliding block puzzles are both well known and popular with puzzle enthusiasts. Likewise, manipulable blocking or interference puzzles are commercially available, attesting to their popularity. Puzzles of these types are exemplified respectively by RUSH HOUR.RTM. (see U.S. Pat. No. Des. 395,468) and SWITCHBACK.RTM. (see U.S. Pat. No. 5,437,454 and U.S. Pat. No. Des. 362,471), puzzles that are produced by Binary Arts, Inc. of Alexandria, Va.
The Japanese designed puzzle called "Crossing the River" produced by Bits & Pieces of Boston, Mass. is another example of this type of puzzle. This puzzle has a plurality of one-sided sliding bars with troughs through which a boat and logs are maneuvered. The housing for the puzzle is a framed rectangular playing surface on which the sliding bars are arranged. One of the drawbacks to this puzzle is that the movable pieces, sliding bars, and playing surface are not uniformly manufactured to provide a smooth fit between the various pieces and bars. Also, if there is a jolt or sudden movement to the puzzle, then the movable pieces and the sliding bars may become dislodged from the playing surface. A more important drawback exists in that the sliding bars are so chosen as to allow only a small number (six) of interesting puzzles.
Notwithstanding the usefulness of the above-described puzzles, a need still exists for a versatile, adjustable, self-retaining, precisely manufactured puzzle for handheld amusement, which allows a large number of interesting challenges of differing degrees of difficulty.